Question

In 1800 the main fuel used in the US was wood. (assume wood cellulose is C6H12O6). In 1900 the main fuel used was coal ( assume coal is pure Carbon) In 2014 the main fuel is oil(assume it is isooctane) Assume that oin 2100 the main fuel will be Hydrogen(H2). Use a spreadsheet to prepare a graph of carbon dioxide releasedper kilojoule of energy produced.(y axis), as a function of year (x axis) from 1850 to 2050

Answer 1

1] For Cellulose,

Combustion reaction:

C6H12O6 + 3O2 -----> 6CO2 + 6H2O

Heat of formation of cellulose = -1250 kJ/mole

Heat of formation of CO2(g) = -393.5 kJ/mole

Heat of formation of H2O(g) = -241.8 kJ/mole

Heat of formation of diatomic gases at standard state = 0

Heat of reaction at standard state

= [6 x heat of formation of CO₂ (g) + 6 x heat of formation of H₂O (g)] - [heat of formation of glucose]

= 6*(-393.5) + 6*(-241.8) - (-1250)

= -2361 - 1450.8 + 1250

= -2561.8 kJ/mole

CO2 released = 6 moles per 2561.8 kJ of energy

2] For Coal,

C(s) + O2(g) -----> CO2(g)

This is nothing but the formation reaction of CO2.

Therefore, the heat of the reaction = heat of formation of CO2 = -393.5 kJ/mole

CO2 produced = 1 mole per 393.5 kJ of energy produced.

3] For isoocatne,

C8H18 + (1/2)O2(g) ----> 8CO2(g) + 9H2O(g)

heat of formation of C8H18 = -255.1 kJ/mol

Heat of combustion of C8H18 = 8*(-393.5) + 9*(-241.8) - (-255.1) = -5069.1 kJ/mol

CO2 produced = 8 mole per 5069.1 kJ of energy

4]

For H2,

H2(g) + (1/2)O2 (g) ----> H2O(l)

The heat of formation of H2O(l) at standard state = -285.8 kJ/mol

CO2 produced = 0 per 285.8 kJ of energy

Molecular weight of CO2 = 12+2*16 = 44 g/mol

fuel	CO2 produced (mol)	Energy produced kJ	mass of CO2 (g)	year	CO2 in g released per kJ of energy
Cellulose	6	2561.8	264	1800	0.103053
Coal	1	393.5	44	1900	0.111817
Isoocatne	8	5069.1	352	2014	0.06944
H2	0	285.8	0	2100	0

Now we will plot the graph